ArticlePDF Available

Abstract and Figures

We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 ± 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 104- to 106-year scale, but a link between oxygen isotope and sea level on the 107-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).
Content may be subject to copyright.
The Phanerozoic Record of Global
Sea-Level Change
Kenneth G. Miller,
1
*
Michelle A. Kominz,
2
James V. Browning,
1
James D. Wright,
1
Gregory S. Mountain,
1,3
Miriam E. Katz,
1
Peter J. Sugarman,
4
Benjamin S. Cramer,
1,5
Nicholas Christie-Blick,
3
Stephen F. Pekar
3,6
We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on
various time scales and present a new sea-level record for the past 100 million years
(My). Long-term sea level peaked at 100 T 50 meters during the Cretaceous, implying
that ocean-crust production rates were much lower than previously inferred. Sea level
mirrors oxygen isotope variations, reflecting ice-volume change on the 10
4
-to10
6
-year
scale, but a link between oxygen isotope and sea level on the 10
7
-year scale must be
due to temperature changes that we attribute to tectonically controlled carbon dioxide
variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry,
and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past
100 My, sea-level changes reflect global climate evolution from a time of ephemeral
Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in
Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern
Hemisphere ice sheets (2.5 Ma to the present).
F
luctuations in global sea level (eustasy)
result from changes in the volume of
water in the ocean or the volume of
ocean basins (Fig. 1) (1–4). Water-volume
changes are dominated by growth and decay of
continental ice sheets, producing high-
amplitude, rapid eustatic changes Eup to 200
m and 20 m per thousand years (ky)^. Other
processes that affect water volume occur at
high rates (10 m/ky) and low amplitudes (È5
to 10 m): desiccation and inundation of mar-
ginal seas, thermal expansion and contraction
of seawater, and variations in groundwater and
lake storage. Changes in ocean basin volume
are dominated by slow variations in sea-floor
spreading rates or ocean ridge lengths (100 to
300 m amplitude, rates of 10 m/My). Variations
in sedimentation cause moderate amplitude
(60 m), slow changes (10 m/My). Emplace-
ment of oceanic plateaus produces moderate-
ly rapid rises (60 m/My) but slow falls due to
thermal subsidence (10 m/My).
Eustatic variations can be estimated from
satellite measurements, tide gauges, shoreline
markers, reefs and atolls, oxygen isotopes
(d
18
O), and the flooding history of continental
margins and cratons. Satellite measurements
are limited to the past 10 years (5), whereas
tide gauge records extend back only È150
years (3). The most recent pre-anthropogenic
sea-level rise began at about 18 ka and can be
measured by directly dating shoreline markers
(fig. S1). Tropical reefs and atolls (fig. S2)
provide the most reliable geological estimates
by dating Bfossil sunshine[ (e.g., shallow-
dwelling corals) and have provided a precise
estimate for the last sea-level lowstand (120 T
5 m below present at 18 ka) (fig. S2) (6, 7).
However, most coral records are from regions
with complicated uplift/subsidence histories,
are difficult to recover and date (particularly
beyond a few 100 ky), and have poorly pre-
served lowstand deposits.
The growth and decay of continental ice
sheets causes eustatic changes that are in-
directly recorded in the chemistry of forami-
nifera because ice has lower d
18
O values than
seawater (fig. S2) Ee.g., (8, 9)^. Oxygen isotope
values provide a proxy for glacioeustasy, but
d
18
O-based reconstructions are subject to
several uncertainties: (i) Calcite d
18
Ovalues
also vary as a function of temperature. (ii)
Surface-ocean d
18
O values are influenced by
local evaporation-precipitation effects on
seawater. (iii) Postdepositional alteration (dia-
genesis) may overprint original d
18
Ovalues,
limiting useful records to sediments younger
than 100 My.
Continents have been flooded many times
in the geologic past (Fig. 2). However, the
flooding record is not a direct measure of
eustatic change because variations in sub-
sidence and sediment supply also influence
shoreline location. Regional unconformities
(surfaces of erosion and nondeposition) divide
the stratigraphic record into sequences and
provide a key to eustatic change. Unconform-
ities result from sea-level fall or tectonic uplift
(10–12). Similar ages of sequence boundaries
on different continents have been interpreted
as indicating that the surfaces were caused by a
global process, eustasy Ee.g. (10, 11)^. The link-
age with d
18
O increases for the past 40 My
(13) indicates that most sequence boundaries
resulted from eustatic falls driven by the
growth of continental ice sheets.
Although unconformities poten-
tially provide the timing of eustatic
lowstands, extracting global sea-
level history from the stratigraphic
record requires a quantitative method
that distinguishes the contributions
of eustasy, subsidence, and sedi-
ment accumulation. Backstripping
is an inverse technique that can be
used to quantitatively extract sea-
level change amplitudes from the
stratigraphic record. It accounts for
the effects of sediment compac-
tion, loading (the response of crust
to overlying sediment mass), and
water-depth variations on basin sub-
sidence (14). Tectonic subsidence at
a passive margin is modeled with
thermal decay curves and removed
REVIEW
1
Department of Geological Sciences, Rutgers University,
Piscataway, NJ 08854, USA.
2
Department of Geo-
sciences, Western Michigan University, Kalamazoo, MI
49008–5150, USA.
3
Lamont-Doherty Earth Observa-
tory of Columbia University, Palisades, NY 10964, USA.
4
New Jersey Geological Survey, Post Office Box 427,
Trenton, NJ 08625, USA.
5
Department of Geological
Sciences, University of Oregon, Eugene, OR 97403–
1272, USA.
6
School of Earth and Environmental
Sciences, Queens College, 65-30 Kissena Boulevard,
Flushing,NY11367,USA.
*To whom correspondence should be addressed:
kgm@rci.rutgers.edu
Fig. 1. Timing and amplitudes of geologic mechanisms of
eustatic change derived from (1–4). SF, sea floor; Cont,
continental.
www.sciencemag.org SCIENCE VOL 310 25 NOVEMBER 2005
1293
to obtain a quantified eustatic estimate in the
absence of local tectonic complexities.
We review the record of and uncertainties
in eustatic changes over the past 543 My on
three time scales: (i) a long-term trend (10
7
to
10
8
years) that has been attributed largely to
variations in sea-floor spreading; (ii) the 10
6
-
year scale that is among the most prominent
features of the stratigraphic record; and (iii) the
10
4
-to10
5
-year scale that is dominated by
changes in ice volume and controlled by astro-
nomical variations in insolation. We present a
new eustatic record for the past 100 My, with
implications for causal mechanisms for both
10
7
- and 10
6
-year changes.
Long-Term Flooding of Continents
Sloss (15) recognized that North America
experienced five major Phanerozoic floodings
(Fig. 2) and attributed these changes to sub-
sidence and uplift of the craton. Vail and col-
leagues at Exxon Production Research Company
(EPR) recognized similar 10
7
-to10
8
-year scale
‘supersequences’ that they attributed to global
sea-level changes (10, 11, 16). Others have re-
constructed continental flooding history on the
10
7
-to10
8
-year scale (4, 17–19) (Fig. 2) and
inferred eustatic changes from commonalities
among continents.
High Late Cretaceous sea level has been
attributed to high ocean-crust production rates
that resulted in more buoyant ridges displacing
seawater onto low-lying parts of continents
(‘‘tectonoeustasy’’) (20). This concept has been
extended to the Paleozoic through Early Meso-
zoic by assuming that 10
7
-to10
8
-year scale
continental flooding was caused by high sea-
floor spreading rates, even though direct evi-
dence for sea-floor spreading rates is absent
owing to subduction.
Our sea-level record for the past 100 My
has much lower amplitudes on the 10
7
-to
10
8
-year scale than previously inferred (Figs.
2 and 3 and fig. S3), with implications for sea-
level change from 543 to 100 Ma. Our 100 to
7 Ma record (Fig. 2) is based on backstripping
stratigraphic data from five New Jersey coast-
al plain coreholes (21, 22). Similar estimates
obtained for each site suggest that we suc-
cessfully accounted for the effects of thermal
subsidence, sediment loading, compaction, and
water-depth variations. Our long-term trend in-
dicates that sea level was 50 to 70 m above
present in the Late Cretaceous (È80 Ma),
roseto70to100mfrom60to50Ma,andfell
by È70 to 100 m since 50 Ma (23). This con-
trasts with previously reported Late Cretaceous
sea-level peaks of about 250 to 320 m based
on sea-floor spreading reconstructions (2), al-
though it is within error estimates of 45 to 365 m
(best estimate 230 m) (24). It is lower than
global continental flooding estimates [150 m
(19), 80 to 200 m (18)].
Our results are similar to backstripped
estimates from the Scotian and New Jersey con-
tinental shelves (14), although the Late Creta-
ceouspeakislower(50to70mversusÈ110 m)
(fig. S3). One-dimensional (1D) backstripping
may underestimate the Late Cretaceous peak
because coastal plain subsidence results from
athermoflexuraleffect(14), and thermal sub-
sidence curves may slightly overestimate the
tectonic portion of subsidence of the older sec-
tion. Considering backstripping and continental
flooding estimates (18, 19) and errors in our
paleowater depth estimates (eustatic error of
T10 to 35 m), we conclude that sea level in the
Late Cretaceous was 100 T 50 m higher than it
is today.
Using new sea-floor age data, Rowley (25)
suggested that there have been no changes in
sea-floor spreading rates over the past 180 My.
Our record implies a modest decrease in the
rate of ocean-crust production because the long-
term eustatic fall of 70 to 100 m since the early
Eocene (Fig. 3) cannot be totally ascribed to
permanent growth of ice sheets (26).
Fig. 2. Comparison of Phanerozoic backstripped eustatic estimates of this
study, Watts (14), Sahagian (35), Kominz (29), Levy (30), and Bond (18);
EPR records of Vail (10)andHaq(11, 16); continental flooding records of
Sloss (15) and Ronov (17) plotted versus area, and Bond (18), Harrison (19),
and Sahagian (4) plotted versus sea level; and evolutionary records compiled
by Katz (52).
R EVIEW
25 NOVEMBER 2005 VOL 310 SCIENCE www.sciencemag.org
1294
Our observation that long-term eustatic
changes were appreciably smaller than previ-
ously thought has implications for geochemical
models [e.g., (27)] that have used sea-level
records to scale ocean production rates. Es-
timates derived from backstripping from the
past 170 My (Fig. 2) show much
lower long-term amplitudes than
those published by EPR. Back-
stripped sea-level records from the
Cambrian-Devonian of the western
United States show È200-m ampli-
tudes on the 10
7
-year scale (28–30)
(Fig. 2), although a Cambrian-
Ordovician backstripped data set
from the Appalachians shows a
lower (È70 m) amplitude (Fig. 2)
(28). The sea-level rise in the
Cambrian is attributed to the gen-
eration of new ocean ridges with
the breakup of Pannotia (29), but
the amplitude of this rise is still
uncertain. Although the jury is still
out on the amplitudes of Paleozoic
sea level on the 10
7
-year scale,
our work suggests that the EPR
records cannot be used to scale
past spreading rates.
Sea-level changes on very
long time scales (250 My) are
related to the assembly and break-
up of supercontinents. Formation
of the supercontinents Pannotia
(late Proterozoic to Early Cambri-
an) and Pangea (Permian to early
Triassic) was associated with low
levels of continental flooding (Fig.
2). This may be attributed to (i) a
eustatic effect due to thickening of
continents during orogeny result-
ing in increased oceanic area (2)
and/or (ii) higher elevations that
result when trapped heat builds up
below the supercontinents (31).
Million-Year Scale Changes
In 1977, EPR surprised academic
and industrial colleagues with the
publication of a Phanerozoic eustatic
record that showed more than 50
falls, some as large as 400 m (10). In
1987, the EPR group published a
series of papers, including a syn-
thesis in Science (11) that reported
more than 100 sea-level falls dur-
ing the past 250 My, with a max-
imum fall of 160 m. The EPR
studies came under intense scru-
tiny because of the novel sugges-
tions that (i) sequence boundaries are time-
important features that could be recognized on
seismic profiles and (ii) seismic profiles could
be used to determine the history of sea level.
The EPR curves have been strongly criticized
for their methodology (12, 32), with critics sug-
gesting that coastal onlap curves presented
cannot be translated into a eustatic estimate.
Drilling on the New Jersey margin has
provided new insights into the amplitudes of
and mechanisms for 10
6
-year scale sea-level
changes. Fourteen Late Cretaceous sequences
and 33 Paleocene-Miocene sequences were
identified in New Jersey coastal plain core-
holes (13, 33) and dated by integrating bio-
stratigraphy, Sr-isotopic stratigraphy, and
magnetostratigraphy to produce a chronology
with age resolution of better than T0.5Myfor
the Cenozoic (13)andT1.0MyfortheLate
Cretaceous (33). Onshore New Jersey se-
quence boundaries correlate with sequence
boundaries in the Bahamas, northwest Europe,
the U.S. Gulf Coast, Russia, offshore New Jer-
sey, and those of EPR, which suggests that
they are global and formed in
response to eustatic falls (13, 33).
Thus, drilling has validated the
number and timing, although
not the amplitude, of many of
the EPR sea-level events for the
past 100 My (13, 33). Oligocene-
Miocene sequence boundaries
can be firmly linked with global
d
18
O increases, demonstrating a
causal relation between sea level
and ice volume (13, 33), as ex-
pected for the Icehouse world of
the past 33 My.
Backstripping of the New
Jersey records provides eustatic
estimates from È100 to 7 Ma
(Fig. 3). Paleocene-Eocene and
Miocene estimates are derived
from 1D backstripped records
from five sites and Late Creta-
ceous sequences from two sites
(34). Several Upper Cretaceous
onshore sections capture full
amplitudes of change; howev-
er, many Cretaceous and most
Cenozoic onshore sections do
not record sea-level lowstands.
Eustatic estimates for the latest
Eocene to earliest Miocene are
derived from 2D backstripping
(22) that addressed this problem.
Our backstripped eustatic es-
timate (table S1) shows that
global sea level changed by 20
to 80 m during the Late Creta-
ceous to Miocene (this study)
and the Middle Jurassic to Late
Cretaceous (35). Our compari-
son shows that the amplitudes of
the EPR sea-level curve, includ-
ing the most recent update (16),
are at least 2.5 times too high
(Fig.2andfig.S3).
Eustatic changes with ampli-
tudes of 10s of meters in less
than 1 My pose an enigma for
a supposedly ice-free Green-
house world, because ice-volume
changes are the only known
means of producing such large
and rapid changes. Our record
(Fig. 3) quantifies high ampli-
tudes and rates of eustatic change (925 m in
G 1 My) in the Late Cretaceous to Eocene
Greenhouse world. Based on the sea-level
history, we have proposed that ice sheets
existed for geologically short intervals (i.e.,
lasting È100 ky) in the previously assumed
Fig. 3. Global sea level (light blue) for the interval 7 to 100 Ma derived by
backstripping data (21). Global sea level (purple) for the interval 0 to 7 Ma derived
from d
18
O,shownindetailonFig.4.Shownforcomparisonisabenthic
foraminiferal d
18
O synthesis from 0 to 100 Ma (red), with the scale on the
bottom axis in ° [reported to Cibicidoides values (0.64° lower than
equilibrium)]. The portion of the d
18
Ocurvefrom0to65Maisderivedusing
data from Miller (44) and fig. S1 recalibrated to the time scale of (71). The d
18
O
curve from 65 to 100 Ma is based on the data compiled by Miller (36) calibrated
to the time scale of (72). Data from 7 to 100 Ma were interpolated to a constant
0.1-My interval and smoothed with a 21-point Gaussian convolution filter using
Igor Pro. Pink box at È11 Ma is sea-level estimate derived from the Marion
Plateau (51). Heavy black line is the long-term fit to our backstripped curve
(23). Light green boxes indicate times of spreading rate increases on various
ocean ridges (57). Dark green box indicates the opening of the Norwegian-
Greenland Sea and concomitant extrusion of the Brito-Arctic basalts.
R EVIEW
www.sciencemag.org SCIENCE VOL 310 25 NOVEMBER 2005
1295
ice-free Late Cretaceous-Eocene Greenhouse
world (36). This view can be reconciled with
previous assumptions of an ice-free world.
Sea-level changes on the 10
6
-year scale were
typically È15 to 30 m in the Late Cretaceous-
Eocene (È100 to 33.8 Ma), suggesting growth
and decay of small- to medium-sized (10 to
15 10
6
km
3
) ephemeral Antarctic ice sheets
(36). These ice sheets did not reach the Ant-
arctic coast; as a result, coastal Antarctica and
deep-water source regions were warm even
though there were major changes in sea level
as the result of glaciation (36). These ice sheets
existed only during ‘cold snaps,’ leaving Ant-
arctica ice-free during much of the Greenhouse
Late Cretaceous to Eocene (36).
Sea-level changes on the 10
6
-year scale
occurred throughout the Phanerozoic. Studies
from the Russian platform and Siberia provide
backstripped records of 10
6
-year sea-level
changes that are remarkably similar to New
Jersey in the interval of overlap and extend to
the Middle Jurassic (È170 Ma) (35). The strat-
igraphic record before 170 Ma is replete in
10
6
-year sea-level changes (16, 37). However, it
is unclear whether these variations represent
global changes in sea level. Eustatic estimates
have been extracted from backstripping of Pa-
leozoic strata (28, 29) (Fig. 2), although differ-
ences in the Appalachian versus the western
U.S. Cambrian-Ordovician sea-level amplitude
estimates are large, and thus the eustatic imprint
is ambiguous.
Eustatic changes on the 10
4
-to10
6
-year
scales were controlled primarily by variations
in ice volume during the past 100 My and
may be expected to be modulated by both
short-period [19/23 (precession), 41 (tilt), and
È100 ky (precession)] and long-period [1.2
(tilt) and 2.4 My (precession)] astronomical
variations (38). Spectral analysis of our sea-
level records shows that variations occur with
an as-yet-unexplained, persistent 3-My beat
and a second primary period varying from 6
to 10 My (fig. S4). Amplitudes in the È3-My
bandwith are È10mfrom60to20Ma,with
lower amplitude from 90 to 60 Ma.
The existence of continental ice sheets in the
Greenhouse world is a controversial in-
terpretation, but the study of ice-volume history
has progressively tracked ice sheets back through
the Cenozoic (36). After extensive debate, a
consensus has developed that ice volume
increased markedly in the earliest Oligocene
(8, 9). We suggest that, at that time, the Ant-
arctic ice sheet began to be a forcing agent of,
and not just a response to, ocean circulation
(36). The Antarctic continent (including west
Antarctica) (39) was entirely covered by ice, and
sea level was lower by È55 m (22). As a result,
latitudinal thermal gradients (40) and deep-water
circulation rates increased [with pulses of
Southern Component and Northern Component
Water (41)]. Diatoms diversified rapidly in
response to increased surface-water circulation
and nutrient availability (Fig. 2), resulting in
increased export production and a positive
feedback on CO
2
drawdown and cooling.
The earliest Oligocene event represented a
major change in climate state from a Greenhouse
world with cold snaps to the Icehouse world that
continues today. Sea-level changes from the
Oligocene to the early Pliocene (È33.8 to 2.5
Ma) were È30 to 60 m (Figs. 3 and 4), with
growth and decay of a large (up to present
volumes of 25 10
6
km
3
) ice sheet mostly in
Antarctica. A middle Miocene d
18
Oincreaseis
associated with deep-water cooling and two
ice-growth events that resulted in the permanent
development of the East Antarctic ice sheet
(40). Northern hemisphere ice sheets (NHIS)
have existed since at least the middle Miocene
(41), but large NHIS with sea-level changes of
60 to 120 m only began during the late Pli-
ocene to Holocene (È2.5to0Ma)(Fig.4).
Milankovitch Scale Changes
The growth and decay of NHIS (the late
Pliocene-Holocene ‘ice ages’’) and attendant
sea-level changes were paced by 10
4
-to10
5
-
year scale Milankovitch changes. The d
18
O
record shows a dominant 100 ky (eccentricity)
beat over the past 800 ky, with secondary 19/23
(precession) and 41-ky (tilt) periods (42). Be-
fore È800 ky, the tilt cycle dominated d
18
O
(43) and sea-level records. Although strong
precessional and eccentricity beats occur in the
carbon system, the tilt cycle has dominated
d
18
O and ice-volume records for much of the
past 33.8 My (9). Growth and decay of small-
to medium-sized ice sheets in the Late
Cretaceous-Eocene on the Milankovitch scale
probably lie near or below the detection limit
of d
18
O records [È 0.1 per mil (°) 0 10-m
eustatic change].
Continental margins record 10
4
-to10
5
-year
scalesea-levelchangesonlyinveryhighsed-
imentation rate settings. Foraminiferal d
18
O
records reflect ice volume in addition to tem-
perature changes and potentially provide a
proxy for sea-level changes on the 10
4
-to
10
5
-year scale. The d
18
O record provides con-
tinuity and excellent age control, although
assumptions about thermal history must be
made to use it as a sea-level proxy. In addition,
diagenesis complicates planktonic foraminiferal
d
18
O records, although benthic foraminifera
generally show little evidence for diagenesis
at burial depths less than 400 to 500 m (44).
We derive sea-level estimates from 9 to
0 Ma using benthic foraminiferal d
18
O records
because the New Jersey record is incomplete
from 7 to 0 Ma (table S1). We scaled the ben-
thic foraminiferal d
18
Orecord(45)tosealevel
by making minimum assumptions about ocean
thermal history (Fig. 4). The resultant sea-level
curve (Fig. 4) aligns remarkably well with the
backstripped record from 9 to 7 Ma (Fig. 3).
Our d
18
O-derived sea-level estimate for the
past 9 My (Fig. 4) shows that the record is
dominated by the response to the 41-ky peri-
od tilt forcing, which increases in amplitude
toward the present, and a low-amplitude È21-ky
precession response. The major 100-ky events
of the past 900 ky stand out in the sea-level
record (Fig. 4). There are prominent 10
6
-year
scale sea-level falls (the 2.5, 3.3, 4.0, 4.9, 5.7,
and 8.2 Ma events) (Fig. 4), but these are not
obviously paced by amplitude modulations of
either precession or tilt (fig. S4).
Suborbital Scale
Very large (9100 m) sea-level rises are associ-
ated with glacial terminations of the past 800 ky
(fig. S1) (6).Themostrecentrisethatfollowed
the last glacial maximum at 18 ka occurred
as two major steps associated with meltwater
pulses (MWP) 1a (13.8 ka) and 1b (11.3 ka),
punctuated by a slowing at È12 ka (6). Sea-
level rise slowed at about 7 to 6 ka (fig. S1).
Some regions experienced a mid-Holocene sea-
level high at 5 ka, but we show that global sea
level has risen at È1 mm/year over the past 5
to 6 ky. We present new core data from New
Jersey covering the past 6 ky that show a rise
of 2 mm/year over the past 5 ky (fig. S1). This
New Jersey curve is remarkably similar to
sea-level records from Delaware (46) and south-
ern New England (47), with a eustatic rise of
1 mm/year over the past 5 ky once corrected
for subsidence effects (48), virtually identical
to that obtained from Caribbean reef localities
(49) (fig. S1) accounting for subsidence.
Error Estimates
Long-term sea-level estimates show consider-
able differences, with a large range of Late
Cretaceous sea-level estimates: È110 m (14),
150 m (19), 250 m (4),and80to200m(18),
and our best estimate of 100 T 50 m. We con-
clude that sea-level amplitudes on this scale
were substantially lower than generally believed
(100 versus 250 m) over the past 170 My, with
uncertain amplitude before this (Fig. 2).
Sea-level estimates on the 10
6
-year scale
have an uncertainty, typically, of at best T10 to
T50 m. The two main sources of errors in
backstripping relate to hiatuses (time gaps) and
paleowater depth estimates. New Jersey coastal
plain sequences represent primarily inner-shelf
to middle-shelf environments, with eustatic
errors from paleowater depth estimates of T10
to 20 m (50). Hiatuses in our record potentially
explain why amplitudes of change might not be
fully recorded, and the effect of hiatuses can be
evaluated only by comparing our record with
other regions. Drilling on the Marion Plateau
(offshore northeast Australia) targeted an È11 Ma
eustatic lowering (51); backstripping yields a
sea-level estimate of 56.5 T 11.5 m for this
event (pink bar on Fig. 3). Our estimate for
this event is È40 T 15 m (Fig. 1); these esti-
mates are consistent, within error, but suggest
that we may underestimate sea-level falls by 5
to 30 m.
R EVIEW
25 NOVEMBER 2005 VOL 310 SCIENCE www.sciencemag.org
1296
The record of the past 130 ky illustrates the
errors in converting a d
18
O record into a sea-
level proxy (fig. S1). Benthic foraminiferal
d
18
O records can be scaled to a faithful proxy
for glacial to cool interglacials [Marine Isotope
Chron (MIC) 2d to 5d] (fig. S2), with sea level
and d
18
O in phase and lagging insolation.
However, large deviations of the d
18
O-based
sea-level curve occur during peak warm in-
tervals (Holocene and MIC 5e) (Fig. 2), with a
hint that deep-sea temperature change leads
sea level. We have attempted to correct for this
temperature effect by scaling to the
Barbados sea-level record (6). How-
ever, this results in underestimating
amplitudes of glacials and overesti-
mating amplitudes of interglacials,
with a resultant 20% uncertainty.
Relation of Sea Level to
Evolution and Climate
Changes
Episodes of supercontinent rifting
and sea-level rise on the 10
7
-to
10
8
-year scale played a role in
phytoplankton evolution since the
Proterozoic by flooding continental
shelves and low-lying inland areas
and increasing the total length of
coastline. The resulting increases in
habitat heterogeneity, ecospace, and
nutrient availability favored plankton
that lived along continental margins.
Accordingly, diversity increases in
phytoplankton (Fig. 2) appear to
correlate with continental rifting of
Pannotia (Early Paleozoic) and
Pangea (Jurassic) (Fig. 2), ultimate-
ly resulting in the three groups of
eukaryotic phytoplankton (cocco-
lithophores, diatoms, and dinoflag-
ellates) that dominate the modern
ocean (52).
Sea-level changes are expected
with beats of 19/23, 41, and 100 ky,
but similar changes on the 10
6
-year
scale (Fig. 3) have puzzled geolo-
gists. Sea-level cyclicity on the 10
6
-
year scale can be explained by a
modulation of the shorter term
Milankovitch-scale sea-level events
(fig. S5). For example, a promi-
nent seismic disconformity spanning
the Oligocene/Miocene boundary
(È23.8 Ma) on the New Jersey slope (13)
can be correlated to a detailed d
18
O record at
deep-sea Site 929 (53), showing that the 10
6
-
year scale sea-level fall at the Oligocene/
Miocene boundary occurred as a series of
41-ky d
18
O increases and sea-level changes.
The 41-ky sea-level falls are reflected in core
photographs by a series of dark-light changes
(fig. S5), resulting from variations in glauco-
nite transported downslope during lowstands.
The seismic reflection is a concatenation of
these beds and the ice-volume events that
caused them.
The high sea levels of the Late Cretaceous
and early Eocene are associated with peak ben-
thic foraminiferal d
18
O values (Fig. 3) (table
S1), and it has long been suggested that sea
level covaries with d
18
O on the 10
7
-year scale
[e.g., (54)]. On the 10
5
-to10
6
-year scales, such
covariance can be explained by ice-volume
changes in concert with temperature changes
(8, 13). However, this cannot be true on the
10
7
-to10
8
-year scale because most of the
d
18
O signal must be attributed to temperature
changes. For example, 3.6° of the 4.4°
increase from 50 to 0 Ma (Fig. 3) must be
attributed to deep-water cooling (15-C overall)
rather than to ice storage (55). The link
between sea level and temperature on the
10
7
-to10
8
-year scale cannot be due to cooling
alone, because this would explain only È15 m
of eustatic fall since 50 Ma. The link between
d
18
O and sea-level variations on the 10
7
-to
10
8
-year scale can be explained by CO
2
variations controlled by tectonics (changes in
ocean-crust production and mountain uplift).
High ocean-crust production rates have
long been linked to high sea level, high CO
2
,
and warm global temperatures [e.g., (54)]. Warm
Late Cretaceous climates and elevated sea
level may be attributable to moderately high-
er sea-floor production rates, although our
results require that crustal production rates
were lower than previously thought. However,
the intensity of spreading ridge hydrothermal
activity (a major source of CO
2
outgassing)
appears also to correlate with
times of major tectonic reor-
ganizations (56). We propose that
the early Eocene peak in global
warmth and sea level (Fig. 3) was
due not only to slightly higher
ocean-crust production but also to
a late Paleocene-early Eocene tec-
tonic reorganization. The largest
change in ridge length of the past
100 My occurred È60 to 50 Ma
(57), associated with the open-
ing of the Norwegian-Greenland
Sea, a significant global reor-
ganization of spreading ridges,
and extrusion of 1 to 2 10
6
km
3
of basalts of the Brito-
Arctic province (58). A late
Paleocene to early Eocene sea-
level rise coincides with this
ridge-length increase, suggesting
a causal relation. We suggest
that this reorganization also in-
creased CO
2
outgassing and
caused global warming to an
early Eocene maximum. Subse-
quent reduced spreading rates
and hydrothermal activity re-
sultedinlowerlong-termsea
level, reduced CO
2
outgassing,
and a cooling of deep-water by
È8-C(44). CO
2
may have been
further lowered by an increase in
continental weathering rates dur-
ing the remainder of the Cenozo-
ic (59), explaining an additional
deep-water cooling of 7-Cto
9-C(44).
Our studies of the past 100
My provide clues to the tempo of
climate and ice-volume changes
for other Icehouse and Green-
house worlds of the Phanerozoic (Fig. 2).
Icehouse worlds of the past 33 My, the Penn-
sylvanian to Early Permian, Late Devonian,
and Late Ordovician (60), can be characterized
by ice-volume changes that caused sea-level
variations up to 200 m. Greenhouse worlds
characterize much of the Phanerozoic, but we
note that small (10 to 15 10
6
km
3
), ephem-
eral ice sheets occurred in the Greenhouse of
the Late Cretaceous to Eocene. This raises
the question as to whether any portion of the
Fig. 4. Oxygen isotopic-based sea-level estimate for the past 9 My.
Isotopic values are reported to equilibrium, with coretop and last glacial
maximum values indicated with arrows and thin vertical green lines. Thin
black line is raw data plotted versus the d
18
O scale (bottom). The purple
line is the sea-level estimate (top scale), which is derived by correcting
the d
18
O data by 0.5° due to a È2-C cooling between 3.3 and 2.5 Ma
(red line), scaling by d
18
O to sea level using a calibration of 0.1°/10 m,
and scaling the result by 0.8 (45).
R EVIEW
www.sciencemag.org SCIENCE VOL 310 25 NOVEMBER 2005
1297
Phanerozoic was ice-free. The Triassic and
Cambrian pose two of the best candidates for
an ice-free world (60), yet Haq (11, 16) noted
numerous 10
6
-year scale sea-level variations
at these times (Fig. 2). If corroborated, these
changes suggest the presence of ephemeral ice
sheets even in the warmest of the Greenhouse
periods.
References and Notes
1. D. T. Donovan, E. J. W. Jones, J. Geol. Soc. (London)
136, 187 (1979).
2. W. C. Pitman III, X. Golovchenko, Soc. Econ. Paleontol.
Mineral. Spec. Publ. 33, 41 (1983).
3. R. Revelle, Ed., Sea-Level Change (National Academy
Press, Washington, DC, 1990).
4. D. Sahagian, M. Jones, Geol. Soc. Am. Bull. 105, 1109
(1993).
5. A. Cazenave, R. S. Nerem, Rev. Geophys. 42, RG3001
(2004).
6. R. G. Fairbanks, Nature 339, 532 (1989).
7. J. Chappell et al., Earth Planet. Sci. Lett. 141, 227
(1996).
8. K. G. Miller, J. D. Wright, R. G. Fairbanks, J. Geophys.
Res. 96, 6829 (1991).
9. J. Zachos, M. Pagani, L. Sloan, E. Thomas, K. Billups,
Science 292, 686 (2001).
10. P. R. Vail et al., Am. Assoc. Petrol. Geol. Mem. 26,49
(1977).
11. B. U. Haq, J. Hardenbol, P. R. Vail, Science 235, 1156
(1987).
12. N. Christie-Blick, G. S. Mountain, K. G. Miller, in Sea-
Level Change, R. Revelle, Ed. (National Academy Press,
Washington, DC, 1990), pp. 116–140.
13. K. G. Miller et al., Rev. Geophys 36, 569 (1998).
14. A. B. Watts, M. Steckler, Ewing Series 3, 218 (1979).
15. L. L. Sloss, Geol. Soc. Am. Bull. 74, 93 (1963).
16. B. U. Haq, A. M. Al-Qahtani, GeoArabia 10, 127 (2005).
17. A. B. Ronov, Am. J. Sci. 294, 802 (1994).
18. G. C. Bond, Tectonophys 61, 285 (1979).
19. C. G. A. Harrison, in Sea-Level Change, R. Revelle, Ed.
(National Academy Press, Washington, DC, 1990),
pp. 141–158.
20. J. D. Hays, W. C. Pitman, Nature 246, 18 (1973).
21. W. A. Van Sickel, M. A. Kominz, K. G. Miller, J. V.
Browning, Basin Res. 16, 451 (2004).
22. M. A. Kominz, S. F. Pekar, Geol. Soc. Am. Bull. 113,
291 (2001).
23. The long-term record was computed as follows: (i) The
median was interpolated at a 0.2 My interval. (ii) A
singular spectrum transform following the description
of the VG algorithm in (61) was applied using a window
length of 65 points (13 My window). (iii) The curve was
reconstructed from the first empirical orthogonal func-
tion resulting from singular spectrum analysis, which
accounts for 58% of total variance in the interpolated
series.
24. M. A. Kominz, Am. Assoc. Petrol. Geol. Mem. 36, 108
(1984).
25. D. B. Rowley, Geol. Soc. Am. Bull. 114, 927 (2002).
26. The development of an ice sheet the size of modern
ice sheets would cause an 80-m fall (62), but this
would only explain a È54-m eustatic fall after ac-
counting for isostatic adjustment.
27. R. A. Berner, Z. Kothavala, Am. J. Sci. 301, 182 (2001).
28. G. C. Bond, M. A. Kominz, M. S. Steckler, J. P. Grotzinger,
Soc. Econ. Paleontol. Min. Spec. Publ. 44, 39 (1989).
29. M. A. Kominz, Basin Res. 7, 221 (1995).
30. M. Levy, N. Christie-Blick, Geol. Soc. Am. Bull. 103,
1590 (1991).
31. D. L. Anderson, Nature 297, 391 (1982).
32. A. D. Miall, J. Sed. Petrology 61, 497 (1991).
33. K. G. Miller et al., Geol. Soc. Am. Bull. 116, 368
(2004).
34. Water-depth changes were inferred from lithofacies
and benthic foraminiferal biofacies studies of (63–66).
35. D. Sahagian, O. Pinous, A. Olferiev, V. Zakaharov, A.
Beisel, Am. Assoc. Petrol. Geol. Bull. 80, 1433 (1996).
36. K. G. Miller, J. D. Wright, J. V. Browning, Mar. Geol.
218, 215 (2005).
37. A. Hallam, Phanerozoic Sea Level Changes (Columbia
Univ. Press, New York, 1992).
38. J. Laskar et al., Astron. Astrophys. 428, 261 (2004).
39. R. V. Dingle, J. M. McArthur, P. Vroon, J. Geol. Soc.
(London) 154, 257 (1997).
40. N. J. Shackleton, J. P. Kennett, Init. Repts. Deep Sea
Drilling Project 29, 743 (1975).
41. J. D. Wright, in Tectonic Boundary Conditions for
Climate Reconstructions, T. J. Crowley, K. Burke, Eds.
(Oxford Univ. Press, New York, 1998), pp. 192–211.
42. J. D. Hays, J. Imbrie, N. J. Shackleton, Science 194,
1121 (1976).
43. M. E. Raymo, B. Grant, M. Horowitz, G. H. Rau, Mar.
Micropaleontol. 27, 313 (1996).
44. K. G. Miller, R. G. Fairbanks, G. S. Mountain, Paleo-
ceanography 2, 1 (1987).
45. Benthic foraminiferal d
18
O records from 846 [0 to 6.136
Ma, equatorial Pacific (67)] and 982 [6.139 to 9 Ma,
northern North Atlantic (68)] were spliced to create a
high-resolution d
18
O composite record with a sample
resolution of 3 ky for the late Miocene to the present.
Although they are located in different deep-water
masses, the records yield similar values across the
splice. The pre–late Pliocene d
18
O record has average
values (2.9°) that are 0.5° lowerthanmodernvalues
(3.4°). Ice volumes during the late Miocene to early
Pliocene were similar to the modern (69), indicating
that this long-term d
18
O offset reflects deep-water
temperatures that were warmer relative to the modern.
Thus, we incrementally added 0.5° to the values older
than 3.5 Ma as a linear function from 2.5 to 3.5 Ma. We
converted the adjusted d
18
O composite record to a
sea-level estimate (Fig. 2) by scaling to a calibration of
0.1°/10 m. Our initial sea-level and d
18
Oestimates
showed a change from the last glacial maximum to
modern changes of 1.5°; this change has been
calibrated in Barbados as 1.2°. The difference is due
to glacial-interglacial deep-sea temperature changes of
È2-C(6), as illustrated on Fig. 3. We scaled the sea-
level curve by 0.8 to account for this difference (Fig. 4).
46. K. W. Ramsey, Delaware Geol. Surv. Rept. of Inves-
tigations 54, 1 (1996).
47. J. P. Donnelly, P. Cleary, P. Newby, R. Ettinger, Geophys.
Res. Lett. 31, L05203 (2004).
48. W. R. Peltier, Rev. Geophys. 36, 603 (1997).
49. R. G. Lighty, I. G. Macintyre, R. Stuckenrath, Coral
Reefs 1, 125 (1982).
50. Paleowater depth estimates are a critical data set needed
for backstripping. Paleowater depth estimates of shallow-
shelf (neritic) environments are relatively precise (T15 m),
but uncertainties increase into middle-shelf (T30 m),
outer-shelf (T50 m), and slope (T200 m) environments.
The errors in paleowater depth estimates correspond to
eustatic errors correcting for loading of T10, 20, 35, and
120 m, respectively. Most of our sections are inner to
middle neritic, with eustatic errors of T10 to 20 m.
51. C. M. John, G. D. Karner, M. Mutti, Geology 32, 829
(2004).
52. M. E. Katz, Z. V. Finkel, D. Grzebyk, A. H. Knoll, P. G.
Falkowski, Annu. Rev. Ecol. Evol. Syst. 35,523
(2004).
53. J. C. Zachos, B. P. Flower, H. Paul, Nature 388, 567
(1997).
54. R. L. Larson, Geology 19, 547 (1991).
55. This assumes that a global equivalent of 0.9° is
stored as ice today (70).
56. M. Lyle, M. Leinen, R. Owen, D. K. Rea, Geophys. Res.
Lett. 14, 595 (1988).
57. S. C. Cande, D. V. Kent, J. Geophys. Res. 97, 13917
(1992).
58. D. G. Roberts, A. C. Morton, J. Backman, Init. Rept.
Deep Sea Drilling Proj. 81, 913 (1984).
59. D. L. Royer, R. A. Berner, I. P. Montan
˜
ez, N. J. Tabor,
D. J. Beerling, GSA Today 14, 4 (2004).
60. L. A. Frakes, E. Francis, J. I. Syktus, Climate Modes of
the Phanerozoic (Cambridge Univ. Press, Cambridge,
1992).
61. M. R. Allen, L. A. Smith, J. Climate 9, 3373 (1996).
62. R. S. Williams, J. G. Ferrigno, U.S. Geol. Surv. Prof.
Pap. 1386-A (1999).
63. K. G. Miller, S. W. Snyder, Proc. ODP, Scientific Results
150X, 1 (1997).
64. K. G. Miller et al., Proc. ODP Init. Rep. 174AX,43
(1998).
65. K. G. Miller et. al., Proc. ODP Init. Rep. 174AXS,1
(1999).
66. K. G. Miller et. al., Proc. ODP Init. Rep. 174AXS,1
(2001).
67. N. J. Shackleton, M. A. Hall, D. Pate, Sci. Res. ODP
138, 337 (1995).
68. D. A. Hodell, J. H. Curtis, F. J. Sierro, M. E. Raymo,
Paleoceanography 16, 164 (2001).
69. D. R. Marchant, G. H. Denton, C. C. Swisher, Geografiska
Annaler 75A, 269 (1993).
70. N. J. Shackleton, J. P. Kennett, Initial Rep. Deep Sea
Drill. Proj. 29, 743 (1975).
71. W. A. Berggren, D. V. Kent, C. C. Swisher, M.-P. Aubry,
Soc. Econ. Paleontol. Mineral. Spec. Publ. 54, 129
(1995).
72. F. M. Gradstein et al., J. Geophys. Res. 99, 24051
(1994).
73. We thank W. Van Sickel and A. Stanley for con-
tributions to development of the sea-level curves,
D. Sahagian for reviews, P. Falkowski and D. Kent for
comments, and the members of the Coastal Plain
Drilling Project (ODP Legs 150X and 174AX) who
are not listed here for contribution of critical data
sets that led to the curve. Supported by NSF grants
OCE 0084032, EAR97-08664, EAR99-09179, and
EAR03-07112 (K.G.M.); EAR98-14025 and EAR03-
7101 (M.A.K.); and the New Jersey Geological Sur-
vey. Samples were supplied by the Ocean Drilling
Program.
Supporting Online Material
www.sciencemag.org/cgi/content/full/310/5752/1293/
DC1
Figs. S1 to S5
Table S1
10.1126/science.1116412
R EVIEW
25 NOVEMBER 2005 VOL 310 SCIENCE www.sciencemag.org
1298
www.sciencemag.org/cgi/content/full/310/5752/1293/DC1
Supporting Online Material for
The Phanerozoic Record of Global Sea-Level Change
Kenneth G. Miller,* Michelle A. Kominz, James V. Browning, James D. Wright,
Gregory S. Mountain, Miriam E. Katz, Peter J. Sugarman, Benjamin S. Cramer,
Nicholas Christie-Blick, Stephen F. Pekar
*To whom correspondence should be addressed: kgm@rci.rutgers.edu
Published 25 November 2005, Science 310, 1293 (2005)
DOI: 10.1126/science.1116412
This PDF file includes:
Figs. S1 to S5
Table S1
References
Figure Captions (Supplementary Online Material)
Fig. S1. Compilation of Holocene relative sea-level records from the western North Atlantic.
Records are from New Jersey (blue/green symbols from this study and red symbols from N.
P. Psuty, Physical Geography, 7, 156 (1986), Delaware (46)southern New England (47), and
a Caribbean reef compilation (49) with a polynomial fit from 8-0 ka (6) and a linear fit from
5-0 ka (this study).
Fig. S2. Comparison sea-level record from the Huon New Guinea terraces (7) and Barbados (6)
and benthic foraminiferal δ
18
O record from Pacific (Carnegie Ridge) core V19-30 (N. J.
Shackleton, N. G. Pisias, in The Carbon Cycle and Atmospheric CO
2
, E. T. Sunquist, W. S.
Broecker, Eds. (American Geophysical Union, Washington, D.C., 1985), pp. 303-317.). Grey
curve at bottom shows variations in insolation for June at 65°N latitude. 0 is modern sea
level.
Fig. S3. Comparison of the sea-level estimate and δ
18
O record from Figure 3 with the sea-level
record of Haq (11), the long-term record of Watts (14) from backstripping of the Scotian
shelf and New Jersey outer continental shelf, and the backstripped record of Sahagian (35)
from the Russian platform and Siberia. Note that the scale for the Haq estimates (green axis)
is 2 times that of our sea-level estimate (blue line and axis). Watts and Sahagian curves are
plotted using the blue axis.
Fig. S4. Spectral content of the sea-level curve. The sea-level curve is shown at the top in black,
with a 0.1 my Gaussian interpolation that was used for spectral analysis shown in red. To the
right is the periodogram of the data in black with the expected red noise spectrum in red. The
image shows variation in spectral power through time calculated using the Gaussian Wigner
Transform implemented by Igor Pro™. Spectral power is indexed to colors according to the
scale in the upper right. Note that the vertical period and frequency axis are log
2
scales, but
with tick marks at linear intervals.
Fig. S5. Benthic foraminiferal δ
18
O data (13) from Ocean Drilling Program Site 904 (NJ
continental slope) plotted versus depth showing magnetic chronozone, core photographs,
reflectivity, and core log impedance. Also shown are δ
18
O records from South Atlantic Site
929 (53) that allow correlation to the Site 904 record. Red curve is plotted versus depth while
the black is plotted versus age scale.
REFERENCES
6. R. G. Fairbanks, Nature 339, 532 (1989).
7. J. Chappell et al., Earth Planet. Sci. Lett. 141, 227 (1996).
11. B. U. Haq, J. Hardenbol, P. R. Vail, Science 235, 1156 (1987).
14. A. B. Watts, M. Steckler, Ewing Series 3, 218 (1979).
35. D. Sahagian, O. Pinous, A. Olferiev, V. Zakaharov, A. Beisel, Am. Assoc. Petrol.
Geol. Bull. 80, 1433 (1996).
46. K. W. Ramsey, Delaware Geol. Surv. Rept. of Investigations 54, 1 (1996).
47. J. P. Donnelly, P. Cleary, P. Newby, R. Ettinger, Geophys. Res. Lett. 31, L05203
(2004).
49. R. G. Lighty, I. G. Macintyre, R. Stuckenrath, Coral Reefs 1, 125 (1982).
53. J. C. Zachos, B. P. Flower, H. Paul, Nature 388, 567 (1997).
0200040006000800010000
Age, yr
Depth, m
New Jersey = 1.9 mm/yr
Delaware
So. New England
Holocene Sea Level,
Western North Atlantic
0
5
10
15
Reefs regression =
1.26 mm/yr
Miller et al., Science, Fig. S1
Caribbean Reefs
other New JerseyIsland Beach
other New JerseyGreat Bay 2
Union BeachCape May
Great BayGreat Bay 1
CheesequakeRainbow Island
3.0
3.5
4.0
4.5
5.0
5.5
δ
18
O ‰
-150
-50
0
50
100
Elevation (m)
0 50 100 150
Age (ka)
1
2
3a
3b
3c
4
5a
5b
5c
6
5d
5e
Insolation
(W/m
2
)
Barbados
New Guinea
450
500
550
Oxygen isotopes, V19-30
Insolation
1
2
NCW-SO
Miller et al., Science, Fig S2
Miller et al., Science Fig. S3
Foram.
P21b
P21a
P14
P22
M2
M3
M4
M5
M7
P18
P19
P16
P20
P15
P12
P11
P10
P9
P7
P6b
P6a
P5
P4c
P4b
P4a
P3b
P3a
P1c
P1b
P1a
Pα-0
M13
PL1
PL5
Pt1a
P13
P17
M1
M6
M12
M9
M14
P2
P8
20
40
60
10
0
30
50
Age (Ma)
70
80
90
100
Epoch/Age
late
middle
early
Oligocene
late
Miocene
earlylate
Eocene
middle
early
Paleocene
late
early
Late Cretaceous
Plio.
Pleis.
e. l.
e.
m.
MaastrichtianCampanianSantonian
Coniacian
Turonian
Cenomanian
14a
Nanno.
1
2
3
4
5
6
7
9
25
24
23
22
21
19
-20
18
17
16
15c
15b
15a
14b
13
12
11
10
9
8
6
5
4
3
2
1
10
11
NP Zones
NN Zones
13
16
19
10
26
24
23
21
20
19
18
14
13
12
11
22
25
9
a
b
c
16
15
17
7
CC Zones
Chrons
Polarity
C6AA
C5AD
C6C
C6B
C6A
C6
C5E
C5D
C5C
C5B
C5A
C5
C13
C12
C11
C10
C9
C8
C7
C15
C17
C7A
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C4A
C4
C3A
C3
C2A
C2
C1
C5AB
C30
C31
C32
C33
C34
C16
-50 0 50 100 150-100
large NHIS
Large Antarctic Ice Sheets
Small Antarctic Ice Sheets
8.2
64.3
57.3
60.8
54.9
53.9
53.2
49.2
48.1
47.0
45.6
42.7
39.7
36.4
34.7
33.7
33.1
32.1
29.9
28.2
26.3
24.1
22.0
20.1
19.5
18.3
16.5
15.4
14.3
13.3
11.0
9.4
97.0
94.7
93.7
92.0
90.0
88.3
86.7
83.0
84.3
83.7
77.5
76.1
71.2
66.9
98.4
5.7
4.9
4.0
3.3
2.5
Kw-Ch
Kw1a
Kw2a
E3
E4
E5
E6
E7
E8
E9
Pa3
Pa4
Pa2
O3
O4
O5
O6
Ch2?
Nav1
Marsh
Merch III
Ch
MII
MI
BIII
BII
BI
MIII
Eng
Pa1
Kw3
Kw0
Haq sea Level (m)
Sea Level (m)
Sahagian
Watts
Haq
-200 0 200
Kw2b/Kw2c
Kw1b/Kw1c
E10/E11
O1/O2
E1/E2
MI/MII
50.7
E6a
Miller et al., Science, Fig. S4
Core-log
impedance
Reflectivity coefficient
Chron
Gray scale
Dark
Light
200
C6C
n1
n2/n3
C7n
1n
C6Br
23.4
24.1
24.6
24.7
25.2
22.3
Sr-isotope
ages (Ma)
Hole 904A
-0.02 0.02
reflection m6
0
Miller et al., Science, Fig. S5
300
304
316
320
Depth (mbsf) (Site 904A)
Age (Ma) (Site 929 only)
Hole 904A
vs. depth
Mi1
12 0
benthic
Site 929,
plotted
vs. age
δ
18
O
26
22
23
24
25
photographs
Cores 33 and 34
308
312
150
... The Cretaceous OAEs, arising from oxygen deficiency, manifest in the extensive accumulation of organic-rich marine shales, leading to notable extinction events among planktonic foraminifera, radiolarians and nanoplanktons (Farouk, Ahmad, and Powell 2017;Keller et al. 2021), alongside significant perturbations in the carbon cycle (Scholle and Arthur 1980;Arthur et al. 1990;Bagherpour et al. 2023). The entombment of organic carbon during OAEs, which selectively enriches lighter isotopic carbon over heavier carbon, is evident through positive peaks in carbon-13 values within sedimentary records (Miller et al. 2005;Forster et al. 2007). Moreover, disruptions linked to sulphur and nitrogen cycles, even in the absence of organic-rich shales, coupled with rising carbon isotope values, offer valuable cues for identifying OAEs and facilitating intercontinental correlations (Voigt et al. 2008). ...
... The Late Cretaceous period is distinguished by the absence of permanent polar ice caps, high global temperatures and elevated levels of atmospheric CO 2 (greenhouse conditions) (Jenkyns 1995;Voigt et al. 2008). Unlike relatively cooler periods of the Early and Late Cretaceous, this interval (Albian-Turonian) is believed to represent the warmest period in the last 140 million years (Miller et al. 2005;Forster et al. 2007;Keller 2008;Petrizzo and Huber 2021). ...
Article
The shallow marine carbonate deposits of the Sarvak Formation have been deposited in an active tectonic setting under warm and humid climatic conditions during the Cenomanian–Turonian (C–T). The focus of this study is on the sedimentological and geochemical analysis of this formation in the Abadan Plain, Zagros Basin. Petrographic studies led to the identification of five microfacies deposited in the restricted lagoon, tidal flat, reef, shoal and open marine environments. They indicate deposition of the Sarvak Formation on a homoclinal ramp–like carbonate platform. Sequence stratigraphy studies have led to the identification of two third‐order sequences named Cenomanian sequence (DSS‐1) and Turonian sequence (DSS‐2), along with six fourth‐order sequences. The upper boundary of DSS‐1, known as the C–T disconformity (CT‐ES), is subjected to meteoric diagenetic processes, as evidenced by meteoric dissolution (karstification), collapsed brecciation and the development of palaeosols. The upper SB of DSS‐2 is marked by the mid‐Turonian disconformity (mT‐ES), characterised by silicification, brecciation, meteoric dissolution and iron oxide staining of core samples. The significant decreases in δ ¹⁸ O carb and δ ¹³ C carb values indicate a strong effect of meteoric diagenesis beneath the palaeoexposure surfaces. The calculation of sea surface temperatures (SSTs) based on the δ ¹⁸ O carb values measured from the unaltered carbonates indicated that the average SST for the C–T is 31.8°C and 30.9°C in K‐01 and K‐02 wells, respectively. A decrease of about 1.5°C is measured during the C–T transition, which indicate a cooling trend of the Late Cretaceous in the Tethyan realm. The carbon isotopic pattern observed in the analysed sections shows correlation with previous studies conducted in the Tethyan region. Additionally, the isotopic composition indicative of Oceanic Anoxic Event 2 (OAE2) is identified around the C–T boundary. Nevertheless, the signature of OAE2 has been somewhat obscured by diagenetic processes associated with C–T palaeoexposure.
... The portion of Earth's topography that is driven by mantle convection, known as dynamic topography, refers to the change in topography that arises from viscous flow within Earth's mantle (figure 1) [4][5][6]. Dynamic changes to Earth's topography are fundamental towards understanding phenomena that include global sea level changes [7,8], the stability of ice sheets [9], sediment transport [10,11] and biodiversity [11]. Here we focus on dynamic topography within Earth's oceans, which is more straightforward to interpret because the oceanic lithosphere contains fewer heterogeneities than the continental lithosphere. ...
Article
Full-text available
Dynamic topography refers to vertical deflections of Earth’s surface from viscous flow within the mantle. Here we investigate how past subduction history affects present dynamic topography. We assimilate two plate reconstructions into TERRA forward mantle convection models to calculate past mantle states and predict Earth’s present dynamic topography; a comparison is made with a database of observed oceanic residual topography. The two assimilated plate reconstructions ‘Earthbyte’ and ‘Tomopac’ show divergent subduction histories across an extensive deep-time interval within Pacific-Panthalassa. We find that introducing an alternative subduction history perturbs our modelled present-day dynamic topography on the same order as the choice of radial viscosity. Additional circum-Pacific intra-oceanic subduction in Tomopac consistently produces higher correlations to the geoid (more than 20% improvement). At spherical harmonic degrees 1–40, dynamic topography models with intra-oceanic subduction produce universally higher correlations with observations and improve fit by up to 37%. In northeast Asia, Tomopac models show higher correlations (0.46 versus 0.18) to observed residual topography and more accurately predict approximately 1 km of dynamic subsidence within the Philippine Sea plate. We demonstrate that regional deep-time changes in subduction history have widespread impacts on the spatial distribution and magnitude of present-day dynamic topography. Specifically, we find that local changes to plate motion histories can induce dynamic topography changes in faraway regions located thousands of kilometres away. Our results affirm that present-day residual topography observations provide a powerful, additional constraint for reconstructing ancient subduction histories.
... (2) Global sea level change Since 1.9 Ma, due to the influence of the ice age, the global temperature has dropped, and the formation of the North and South polar ice sheet has led to sea level fall. During this time, the sea level of QDNB underwent fluctuations [56,57]. The vertical evolution of the shelf-edge trajectory in QDNB show strong relation with sea level changes. ...
Article
Full-text available
The shelf-edge trajectory is comprehensively controlled by tectonics, sediment supply, sea level, and climate fluctuations; its migration and evolution have a strong influence on what happens in the deep-water depositional system during the Quaternary. The shelf-edge trajectory pattern, sediment-budget partitioning into deep-water areas, and reservoir evaluations are focused topics in international geosciences. In this paper, the Qiongdongnan Basin (QDNB) in the northern South China Sea is taken as an example to study how shelf-edge trajectory migration patterns can influence the types of deep-water gravity flow which are triggered there. Through quantitatively delineating the Quaternary shelf-edge trajectory in the QDNB, four types of shelf-edge trajectory are identified, including low angle slow rising type, medium angle rising type, high angle sharp rising type, and retrogradation-slump type. A new sequence stratigraphic framework based on the migration pattern of shelf-edge trajectory is established. There are four (third-order) sequences in the Quaternary, and several systems tracts named lowstand systems tract (LST), transgressive systems tract (TST), and highstand system tract (HST) are identified. This study indicates that the type of deep-water gravity flow can be dominated by the shelf-edge trajectory migration patterns. When the shelf-edge trajectory angle (α) ranged between 0° and 4°, the continental canyons were mostly small-scaled and shallowly incised, with multiple large-scale sandy submarine fan deposits with few MTDs found in the deep-water area. When the angle (α) ranged from 4° < α < 35°, the size and incision depth of the continental slope canyons increased, relating to frequently interbedded sandy submarine fan deposits and MTDs. When angle (α) ranged from 35° < α < 90°, only a few deeply-incised canyons were present in the continental slope; in this condition, large-scaled and long-distance MTDs frequently developed, with fewer submarine fans deposits. When angle (α) ranged from 90° < α < 150°, the valley in the slope area was virtually undeveloped, sediments in the deep-sea plain area consisted mainly of large mass transport deposits, and submarine fan development was minimal. Since the Quaternary, the temperature has been decreasing, the sea level has shown a downward trend, and the East Asian winter monsoon has significantly enhanced, resulting in an overall increase in sediment supply in the study area. However, due to the numerous rivers and rich provenance systems in the west of Hainan Island, a growing continental shelf-edge slope has developed. In the eastern part of Hainan Island, due to fewer rivers, weak provenance sources, strong tectonic activity, and the subsidence center, a type of destructive shelf-edge slope has developed. The above results have certain theoretical significance for the study of shelf-edge systems and the prediction of deep-water gravity flow deposition type.
... During the Late Cretaceous, the long-term global sea level decreased from Campanian to Maastrichtian (Miller et al., 2005;Müller et al., 2008;Haq, 2014). In the Tajik and southwestern Tarim basins, palaeoenvironmental studies on the Upper Cretaceous strata show transgressioneregression cycles that match global sealevel changes (Xi et al., 2016;Kaya et al., 2020). ...
... The Cretaceous System as well as representing a long period of time, was, generally, quite warm with various levels of 'greenhouse' -or even 'hothouse'conditions being described (Friedrich et al. 2012;Huber et al. 2018). Sea levels, as a result, were unusually high as were levels of pCO2 in the atmosphere (Royer et al. 2004;Miller et al. 2005;Haq 2014, and references therein; Scotese et al. 2024), balanced by a lowered pH (Hönisch et al., 2012;Wang et al. 2014, and references therein) but often with a high level of carbonate saturation in the Cretaceous oceans. ...
Article
The Cretaceous System was first established by Jean Baptiste Julien d'Omalius d'Halloy based on his geological mapping of France and the adjacent areas of the Low Countries and Northern Italy. His map, which was published in 1822, has a legend with a rock unit identified as ‘ Terrain Crétacé ’ and that was the birth of the Cretaceous System that we still use today. Unlike many of the other geological systems, there was no definitive publication. The Cretaceous, as currently defined, occupies the interval of time from 145 Ma to 66 Ma, making it one of the longest in the Phanerozoic. The Cretaceous includes both icehouse and greenhouse (even hothouse) conditions and much of the time is characterised by exceptionally high sea levels.
... The Eocene Thermal Maximum 2 (ETM-2 or ELMO), an early Eocene hyperthermal event (Lourens et al. 2005), resulted in an eustatic sea-level rise (Sluijs et al. 2008). A 75 m eustatic sea-level rise during ETM-2 has been widely documented (Miller et al. 2005;Kominz et al. 2008). The biostratigraphic zone of the Kheir Formation is roughly contemporaneous with the onset of the ELMO event, as evidenced by the published data. ...
Article
Full-text available
The depositional history of the central-eastern Sirt Basin of Libya during the Middle Paleocene to Early Eocene is characterised by the deposition of shallow-marine carbonates and hemipelagic claystone and marlstone. To gain a better understanding of the depositional history during this period, we dated the hemipelagic marlstones using planktonic foraminifera and calcareous nannoplankton to refine the stratigraphic relationships with the intercalated shallow-marine limestones. During the Danian, a broad carbonate shelf formed in the eastern sector of the basin. Transgression in the Early Selandian resulted in the deposition of claystones and limestones. The shallow-marine carbonate factory recovered rapidly during the Early-Middle Selandian, forming the Upper Sabil carbonate ramp, however, it became subaerially exposed and eroded in the shallowest areas. The resulting domal structures represent carbonate ramp erosional relics as demonstrated by biostratigraphic results combined with microfacies studies. Whereas in the deeper-water areas of the Upper Sabil carbonate ramp, the deposition was probably continuous throughout the Paleocene–Eocene, the shallow-marine limestones were exposed for about 6 Ma until they were drowned in the Early Eocene. A distinct argillaceous unit, with intercalated shallow-marine limestone beds, was deposited in the basinal areas between the domal structures during the Late Selandian–Thanetian stages. In this study, we define this deposits as the Intisar Formation. The overlying Late Paleocene/Eocene Harash Formation consists of shallow-marine limestones. This trangressive unit infilled the Upper Sabil paleotopography with a 2.5 Ma stratigraphic gap. The hemipelagic marlstone of the Kheir Formation was deposited above the Harash Formation and partly above the Upper Sabil paleotopography during the Ypresian, driven by the major sea-level rise following the Eocene Thermal Maximum-2 (ETM-2). Therefore, a substantial stratigraphic gap of at least 6 Ma is documented on the crest of the domal structures, which were subsequently overlain by the Kheir Formation. Graphical abstract
Article
Full-text available
Introduction The quantitative distribution of grain size of sediments could imply the hydrodynamic conditions as well as terrestrial material composition; and thus, it is indicative of sea-level fluctuations, regional sources and climate changes. The environmentally sensitive components extracted from grain size data serve as excellent indicators of the sedimentary environment and monsoon intensity. Material and methods The drilling data from the shelf margin of the northwestern Qiongdongnan Basin provide an excellent opportunity for studying hydrodynamics and climate change in the Quaternary South China Sea (SCS). The 49 obtained samples of Quaternary sediments are primarily composed of clay and silt, with a low sand content. The environmentally sensitive components are extracted from the sediment samples, based on multiple attempts including grain size-standard deviation, the end-member modelling analysis and the principal component factor analysis methods. Results The increased grain size as supplemented by ratios of rolling movement on the sediment probability accumulation curves indicate enhanced hydrodynamic conditions in the Quaternary northwestern SCS. The alternative indicators of the Quaternary East Asian monsoon are obtained after a comprehensive comparative analysis. The changes in the content of the grain size components of 5.21-6.72 μm and 27.4-35.3 μm are used as the proxy indicators for the Quaternary East Asian summer and winter monsoon of the NW-SCS, respectively. It is likely indicated that the East Asian winter monsoon remarkably strengthened since 1.3 Ma but reached its maximum intensity around 0.8 Ma. During this period, the magnitude of both climatic temperature and sea-level fluctuations are significant, thus, the coarse-grained component increased at falling or low sea-level stages. Discussion The grain size characteristics of the Quaternary shelf margin sediments are indicative of hydrodynamic conditions, source-sink systems and environmental monsoon climate changes in the northwestern SCS.
Article
Full-text available
Leg 81 drilling results on the west margin of Rockall Plateau, combined with available geophysical data, provide the first transect of the 'dipping reflector' type of passive margin. Unlike passive margins characterized by large tilted fault blocks, this type is characterized by an oceanward dipping suite of reflectors and may be the predominant type of rifted margin. The 'dipping reflector' margin can be divided into four structural zones: the ocean crust (Zone I), an outer high (Zone II), the area of dipping reflectors (Zone III), and a 'landward' zone (Zone IV) of subhorizontal reflectors. The Leg 81 transect sampled Zones II, III, and IV at four sites. The Leg 81 results neither prove nor disprove that the dipping reflectors are underlain by oceanic or continental crust, although preliminary gravity interpretation favors the latter. However, the Leg 81 results provide data and in turn constraints on reasonable models for the formation of this type of margin. -from Authors
Article
Full-text available
Commonly it is assumed that the intensity of mid-ocean ridge hydrothermal activity should correlate with spreading rate, since high spreading rates are an indication of large subcrustal heat sources needed for intense hydrothermal activity. We have tested this hypothesis by modeling the deposition of hydrothermal precipitates from cores from Deep Sea Drilling Project Leg 92, taken on the west flank of the East Pacific Rise at 19°S. Although spreading rates at the East Pacific Rise and its predecessor, the Mendoza Rise, have varied by only 50% in the last 30 million years, we found certain episodes, at about 25, 18, 14, and 9 million years ago, of hydrothermal manganese deposition as much as a factor of 20 higher than equivalent Holocene accumulation. These eposides do not correlate with spreading rate changes and instead seem to occur at times of major tectonic reorganizations. We propose that ridge jumps and changes of ridge orientation may substantially increase hydrothermal activity by fracturing the ocean crust and providing seawater access to deep-seated heat sources.
Article
Full-text available
Throughout the latter half of the Pleistocene epoch of Earth history, beginning ∼900 kyr ago, the climate system has been dominated by an intense oscillation between full glacial and interglacial conditions. During each glacial stage, global sea level fell by ∼120 m on average, as extensive ice sheets formed and thickened on the surfaces of the continents at high northern (primarily) and southern latitudes. Within each cycle this glaciation phase lasted ∼90 kyr and was followed by a much more rapid deglaciation event which terminated after ∼10 kyr and which returned the system to the interglacial state. The period of the canonical glacial cycle has remained very close to 100 kyr since its inception in mid-Pleistocene time. Because of the magnitude of the mass that was redistributed over the surface of the Earth during each such glacial cycle and because of the viscoelastic nature of the rheology of the planetary mantle, these shifts in surface mass load induced variations in the shape of the planet that have been indelibly transcribed into the geological record of sea level variability. Indeed, the geological, geophysical, and even astronomical signatures of this process, which is continuing today, are now being measured with unprecedented precision using the methods of space geodesy and have thereby begun to provide important new scientific insight and understanding, both of the interior of the solid Earth and of the climate system variability with which the ice ages themselves are associated. In this article my purpose is to bring together, in a single review, an assessment of where we currently stand scientifically with regard to understanding both of these aspects of the ice ages. Although the discussion will not address in any detail the fascinating issue of ice age climate, since this topic is sufficiently complex of itself to require a detailed review of its own, I will nevertheless attempt to briefly summarize the current state of understanding of the physical processes that are responsible for the occurrence of the ice age cycle, by way of providing a more complete context in which to appreciate the main lines of argument that will be developed.
Article
Full-text available
Field and geochronologic evidence indicate that large and broadly homogeneous plutons can accumulate incrementally over millions of years. This contradicts the common assumption that plutons form from large, mobile bodies of magma. Incremental assembly is consistent with seismic results from active volcanic areas which rarely locate masses that contain more than 10% melt. At such a low melt fraction, a material is incapable of bulk flow as a liquid and perhaps should not even be termed magma. Volumes with higher melt fractions may be present in these areas if they are small, and this is consistent with geologic evidence for plutons growing in small increments. The large melt volumes required for eruption of large ignimbrites are rare and ephemeral, and links between these and emplacement of most plutons are open to doubt. We suggest that plutons may commonly form incrementally without ever existing as a large magma body. If so, then many widely accepted magma ascent and emplacement processes (e.g., diapirism and stoping) may be uncommon in nature, and many aspects of the petrochemical evolution of magmatic systems (e.g., in situ crystal fractionation and magma mixing) need to be reconsidered.
Article
Full-text available
Quantitative analysis of tectonic subsidence in Cambrian and Ordovician platform carbonates and associated strata exposed in the Spring Mountains (Nevada) and the Nopah, Funeral, and Inyo Ranges (California) indicates that subsidence associated with this segment of the early Paleozoic passive continental margin is exponential in form, consistent with thermal contraction of the lithosphere following extension. -from Authors
Article
Full-text available
δ18Obenthic values from Leg 194 Ocean Drilling Program Sites 1192 and 1195 (drilled on the Marion Plateau) were combined with deep-sea values to reconstruct the magnitude range of the late middle Miocene sea-level fall (13.6 11.4 Ma). In parallel, an estimate for the late middle Miocene sea-level fall was calculated from the stratigraphic relationship identified during Leg 194 and the structural relief of carbonate platforms that form the Marion Plateau. Corrections for thermal subsidence induced by Late Cretaceous rifting, flexural sediment loading, and sediment compaction were taken into account. The response of the lithosphere to sediment loading was considered for a range of effective elastic thicknesses (10 < T e < 40 km). By overlapping the sea-level range of both the deep-sea isotopes and the results from the backstripping analysis, we demonstrate that the amplitude of the late middle Miocene sea-level fall was 45 68 m (56.5 ± 11.5 m). Including an estimate for sea-level variation using the δ18Obenthic results from the subtropical Marion Plateau, the range of sea-level fall is tightly constrained between 45 and 55 m (50.0 ± 5.0 m). This result is the first precise quantitative estimate for the amplitude of the late middle Miocene eustatic fall that sidesteps the errors inherent in using benthic foraminifera assemblages to predict paleo water depth. The estimate also includes an error analysis for the flexural response of the lithosphere to both water and sediment loads. Our result implies that the extent of ice buildup in the Miocene was larger than previously estimated, and conversely that the amount of cooling associated with this event was less important.
Article
Full-text available
We present an integrated geomagnetic polarity and stratigraphic time scale for the Triassic, Jurassic, and Cretaceous periods of the Mesozoic Era, with age estimates and uncertainty limits for stage boundaries. The time scale uses a suite of 324 radiometric dates, including high-resolution Ar-40/Ar-39 age estimates. This framework involves the observed ties between (1) radiometric dates, biozones, and stage boundaries, and (2) between biozones and magnetic reversals on the seafloor and in sediments. Interpolation techniques include maximum likelihood estimation, smoothing cubic spline fitting, and magnetochronology. The age estimates for the 31 stage boundaries (in mega-annum) with uncertainty (millions of years) to 2 standard deviations, and the duration of the preceding stages (in parentheses) are Maastrichtian/Danian (Cretaceous/-Cenozoic) is 65.0 +/- 0.1 Ma (6.3 m.y.), Campanian/Maastrichtian is 71.3 +/- 0.5 Ma (12.2 m.y.), Santonian/Campanian is 83.5 +/- 0.5 Ma (2.3 m.y.), Coniacian/Santonian is 85.8 +/- 0.5 Ma (3.2 m.y.), Turonian/Coniacian is 89.0 +/- 0.5 Ma (4.5 m.y.), Cenomanina/Turonian is 93.5 +/- 0.2 Ma (5.4 m.y.), Albian/Cenomanian is 98.9 +/- 0.6 Ma (13.3 m.y.), Aptian/Albian is 112.2 +/- 1.1 Ma (8.8 m.y.), Barremian/Aptian is 121.0 +/- 1.4 Ma (6.0 m.y.), Hauterivian/Barremian is 127.0 +/- 1.6 Ma (5.0 m.y.), Valanginian/Hauterivian is 132.0 +/- 1.9 Ma (5.0 m.y., Berriasian/Valanginian is 137.0 +/- 2.2 Ma (7.2 m.y.), Tithonian/Berriasian (Jurassic/Cretaceous) is 144.2 +/- 2.6 Ma (6.5 m.y.), Kimmeridgian/Tithonian is 150.7 +/- 3.0 Ma (3.4 m.y.), Oxfordian/Kimmeridgian is 154.1 +/- 3.2 Ma (5.3 m.y.), Callovian/Oxfordian is 159.4 +/- 3.6 Ma (5.0 m.y.), Bathonian/Callovian is 164.4 +/- 3.8 Ma (4.8 m.y.), Bajocian/Bathonian is 169.2 +/- 4.0 Ma (7.3 m.y.), Aalenian/Bajocian is 176.5 +/- 4.0 Ma (3.6 m.y.), Toarcian/Aalenian is 180.1 +/- 4.0 Ma (9.5 m.y.), Sinemurian/Pliensbachian is 195.3 +/- 3.9 Ma (6.6 m.y.), Hettangian/Sinemurian is 201.9 +/- 3.9 Ma (3.8 m.y.), Rhaetian/Hettangian (Triassic/Jurassic) is 205.7 +/- 4.0 Ma (3.9 m.y.), Norian/Rhaetian is 209.6 +/- 4.1 Ma (11.1 m.y.), Carnian/Norian is 220.7 +/- 4.4 Ma (6.7 m.y.), Ladinian/Carnian is 227.4 +/- 4.5 Ma (6.9 m.y.), Anisian/Ladinian is 234.3 +/- 4.6 Ma (7.4 m.y.), Olenekian/Anisian is 241.7 +/- 4.7 Ma (3.1 m.y.), Induan/Olenekian is 244.8 +/- 4.8 Ma (3.4 m.y.), Tatarian/Induan (Permian/Triassic) is 248.2 +/- 4.8 Ma. The uncertainty in the relative duration of each individual stage is much less than the uncertainties on the ages of the stage boundaries.
Article
An ⁴⁰Ar/³⁹Ar chronology of in-situ to near in-situ volcanic ashfall deposits indicates that the surficial stratigraphy of Arena Valley extends back at least to middle-Miocene time. Wet-based glacial ice occupied part of Arena Valley more than 11.3 Ma ago. Thick, northeast-flowing ice subsequently engulfed Arena Valley, again more than 11.3 Ma ago. Only minor glacier expansion occurred during Pliocene and Pleistocene time. The maximum Pliocene thickening of Taylor Dome, 35 km inland of Arena Valley, was certainly less than 475 m and probably less than 250 m. Maximum thickening of Taylor Dome was less than 160 m during the Pleistocene. The preservation of Miocene-and Pliocene-age ashes on steep valley slopes indicates that the major bedrock land-forms of Arena Valley are relict and that little slope evolution/colluviation has occurred during the last 11.3 Ma. The geologic record of Arena Valley glaciation and landscape evolution shows persistent cold-desert conditions and hence implies stability of the adjacent East Antarctic Ice Sheet for at least the last 11.3 Ma.
Article
We developed a Late Cretaceous sealevel estimate from Upper Cretaceous sequences at Bass River and Ancora, New Jersey (ODP [Ocean Drilling Program] Leg 174AX). We dated 11-14 sequences by integrating Sr isotope and biostratigraphy (age resolution +/-0.5 m.y.) and then estimated paleoenvironmental changes within the sequences from lithofacies and biofacies analyses. Sequences generally shallow upsection from middle-neritic to inner-neritic paleodepths, as shown by the transition from thin basal glauconite shelf sands (transgressive systems tracts [TST]), to medial-prodelta silty clays (highstand systems tracts [HST]), and finally to upper-delta-front quartz sands (HST). Sea-level estimates obtained by backstripping (accounting for paleodepth variations, sediment loading, compaction, and basin subsidence) indicate that large (>25 m) and rapid (much less than1 m.y.) sea-level variations occurred during the Late Cretaceous greenhouse world. The fact that the timing of Upper Cretaceous sequence boundaries in New Jersey is similar to the sea-level lowering records of Exxon Production Research Company (EPR), northwest European sections, and Russian platform outcrops points to a global cause. Because backstripping, seismicity, seismic stratigraphic data, and sediment-distribution patterns all indicate minimal tectonic effects on the New Jersey Coastal Plain, we interpret that we have isolated a eustatic signature. The only known mechanism that can explain such global changes-glacio-eustasy-is consistent with foraminiferal delta(18)O data. Either continental ice sheets paced sea-level changes during the Late Cretaceous, or our understanding of causal mechanisms for global sea-level change is fundamentally flawed. Comparison of our eustatic history with published ice-sheet models and Milankovitch predictions suggests that small (5-10 x 10(6) km(3)), ephemeral, and areally restricted Antarctic ice sheets paced the Late Cretaceous global sea-level change. New Jersey and Russian eustatic estimates are typically one-half of the EPR amplitudes, though this difference varies through time, yielding markedly different eustatic curves. We conclude that New Jersey provides the best available estimate for Late Cretaceous sea-level variations.